The present invention relates to the science of optics which is the study of the nature and behavior of light. More specifically, the present invention relates to protective lenses called "sun glasses" for shielding the eyes from the sun.
In the past, it has generally been known to "polarize" lenses in order to reduce glare on reflected light. This is done by means of double refraction wherein light is split into two beams.
Typically, sun light is regarded as unpolarized and various dichroic polarizing materials have been used in the past.
Bigradient coatings have been used but not in combination with polarization films because the heat necessary for applying bigradient coatings destroys polarization films.
U.S. Pat. No. 2,409,356 describes a coating for lenses applied as a film on upper and lower portions of the lenses by a high vacuum thermal evaporation process. The problem with this process is that polarization films cannot also be applied to the lenses because of the high temperature requirements necessary to deposit the bigradient material.
U.S. Pat. No. 2,675,740 describes another lens using a high vacuum thermal evaporation process, but the coating is of uniform thickness and different reflective properties are achieved by subjecting the lens to electric glow discharge oxidation.